The overall theme of the book, is the beliefs of the Duggar family, the sisters particularly. They say that how they handle relationships is the key to life in their big family. They talk about relationships with self, parents, siblings, friends, boys, and God.

The Duggar family works with something they call the Buddy system, and that is outlined in the book, as is how the siblings handle conflict.

The Duggars have made a career out of saying gay and trans people are perverts who molest children.
How you feelin' @joshduggar?

Of particular interest in light of the recent Josh Duggar scandal is the sections on the sisters' need to forgive their siblings.

“Even though we may not feel like forgiving someone, we must choose to forgive every person who offends us and do it before they ask — and regardless if they ever do ask. The choice to forgive doesn’t always free the other person from the consequences of his or her wrong actions, but it frees the forgiver of negative feelings towards the offender. And if we still have feelings of bitterness, the Bible says it’s not only to forgive the other person, but also to go a step further and look for ways to bless him or her."

Might Jill Duggar or any of these sisters have had Josh Duggar's instances of molestation in mind when they wrote this?

We shouldn't judge the Duggars till we hear the whole story. Like maybe they had so many kids because some were just for molesting.